The DB25b is a transformer balanced, passive direct box. It features a Ground Lift switch for hum elimination, and an Attenuator control for padding the input signal from -20dB to -infinity dB. Padding the input signal provides a way to connect the DB25b to a line level signal, even a speaker level signal and connecting it to a balanced line or Mic input on a mixer. The two 1/4 inch; inputs are paralleled pass-throughs to also send the input signal to a tuner, pre amp, etc.